The shares for the x13 algo are less than one, and our backend was designed for > 1 share difficulty. I started with:

(workerstat.shares)
and had to modify the multiplier for x13
(workerstat.shares*4096)

As the shares come in, they are extremely low, somewhere around .002 for ~10MH/s rig. That being said, the invalid shares I tried to match from the backend output and "guess" the multiplier, since I have not found an official multiplier setting yet for x13 coins. I have gotten the share numbers very, very close (maybe off by 1 every 1000 shares) and the invalids are, well, a little more off. When I check, the percentages seem to be pretty close, albeit I'm not looking at only one particular address (such as yours).

tl;dr All of your shares are counted and paid out. I'm still working on the valid/invalid multiplier.